Method and apparatus for detecting incipient short circuit conditions in electrolytic cells

ABSTRACT

Method and apparatus for detecting the existence of short circuit conditions between adjacent electrodes positioned in an electrolytic cell. Electrolytic cells of the type characterized by an anode and a cathode, both of which are substantially immersed in a suitable electrolyte, not infrequently develop short circuit conditions caused by physical contact between adjacent electrodes. Incipient short circuit conditions in an electrolytic cell are detected prior to the earliest time of detectability by using prior-art measurements, by scanning the surface of the cell with an infrared sensing apparatus at conditions of scan which permit detection of the thermal abnormality created by the existence of the short circuit condition. The present method and apparatus is useful to scan a large number of electrolytic cells as found in a production facility, so that each of such cells can be rapidly evaluated to determine the possible existence of incipient short circuit conditions.

. 3,809,902 [451 May7, 1974 METHOD AND APPARATUS FOR Primary Examiner-James W. Lawrence Assistant Examiner-I-Iarold A. Dixon DETECTING INCIPIENT SHORT CIRCUIT CONDITIONS IN ELECTROLYTIC CELLS [75] Inventors: Daniel B. Cofer; Bruce E. Betterto Attorney, Agent, or Firm-Jones, Thomas & Askew ABSTRACT Method and apparatus for detectin sh both of Carrollton, Ga.

' t [73] Asslgnee gran hwlre Company, Carrollton, g the existence of ort circuit conditions between adjacent electrodes scanning the surface of the cell with an infrared sens- [56] References Cited ing apparatus at conditions of scan which permit de- N E S S A N S tection of the thermal abnormality created by the existence of the short circuit co method and apparatus is useful ndition. The present 8866 11 3333 0000 5555 2222 m MS m N H "O n" m WT a m H m a TW n L ammwB mf mU mmnN R O 9 E 75 7666 9999 T HHHHO 9096 2299 4040 098 3504 5 3333 of electrolytic cells as found in a produc so that each of such cells can be rapidl determine the possible existence of inc cuit conditions.

Infra Red Scans For Inner Defects, by Malim Reprintfrom Iron Age, May 27, 1965.

I 18 Claims, 4 Drawing Figures PATENTEI] W 7 I974 SHEEI 1 [IF 3 CRT DISPLAY FACSIM RECO vmzo SIGNAL FIG 3 POSITION SYNC.

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1 METHOD AND APPARATUS FOR DETECTING INCIPIENT SHORT CIRCUIT CONDITIONS IN ELECTROLYTIC CELLS This invention relates in general to the detection of short circuit conditions and in particular to the detection of incipient short circuit conditions as found in electrolytic cells used in metal refining operations.

The art of electroplating, in additionto being useful for the application of a relatively thin outer metallic coating on a base or substrate metal, is also of known utility in the refining of metals such as copper. In the electrolytic refining of copper, relatively impure copper anodes are prepared by a conventional casting process and are placed in tanks containing a suitable electrolytic solution such as copper sulphate. The tanks are I also provided with suitable cathodes, which typically may consist of relatively pure, thin copper starter sheets. The relatively impure copper anodes and the relatively pure copper cathodes are connected to a suitable source of electrical current, and the copper is plated from the anodes onto the so-called starter sheets, resulting in cathode sheets of relatively pure copper which are removed from the electroplating tanks for subsequent use.

The electrolytic refining of copper or other metals at production quantities generally requires large numbers of electr'olytic'cells each containing a number of anodes and cathodes, and the proper operation of each cell depends upon the accurate control of the electric current density between the various anodes and cathodes. It is known to those skilled in the art that short circuits can occur between an adjacent anode and cathode, and such short circuits create a preferential path of current flow in the localized area of the short circuit which raises the current density at such location to a level which is greater than the optimum desired current density. Such short circuits can occur from a number of causes, such as inaccurate initial placement of an ad.- jacent anode, and cathode, buckling of the relatively thin cathode starter sheet, or the growth of copper nodules growing from a cathode to touch an adjacent anode during the process of electrolytic refining.- Whateverthe cause of the short-circuit condition, themetallic cathode which is produced as aresult ofa short circuit fails to have the desired metallurgical properties, withthe result thatsuch unacceptable cathodes must be remelted into relatively impure copper anodes and again. subjected to the electrolytic refining process. This means that the electricity initially used in the elec trolytic preparation of the defective cathode, as well as the electricity or other fuel used in remelting such cathode, has been wasted along with the attendant waste in time and other expense resulting from production of a defective cathode.

Prior art efforts to detect the presence of shortcircuit conditionsinelectrolytic refining cells have generally involved the'use of a portable gauss meter and/or voltmeter measurement of individual cell power condi tions. The voltmeter is used in the conventional manner to measure the voltage across each individual electrolytic cell, with 'an abnormally high or low voltage reading being indicative of either an open-circuit or shortcircuit cell condition, respectively. While an opencircuit cell condition, which can be caused by factors such as ineffective contact between a cell electrode and a power supply bus, does not waste electrical power, it will be appreciated that an open-circuit cell is nonproductive of refined metal and represents a defective situation requiring detection and correction. The gauss meter, which those skilled in the art will recognize as an instrument for measuring the field surrounding a conductive member through which electrical current'is flowing, is similarly used in prior-art inspection of electrolytic refining tanks to measure the current flowing through the anode and cathode plates. Prior-art gauss meter measuring techniques require the services of an inspector who manually passes the gauss meter over the anode and cathode plates of each individual tank in an attempt to detect the existence of an abnormal current condition associated with one or more plates.

It is apparent from the foregoing; description of prior art technique that several individual manual measurements are required to be made at each and every cell of an electrolytic refining operation each day, if the proper operating condition of the cells is to be evaluated and maintained. The resulting requirements for inspection manpower are very large, especially since commercial production capabilities of electrolytic refining typically call for a large number of individual cells and cell electrodes. For example, an installation for the electrolytic refining of copper mayhave a plurality of bay work areas, with each bay housing 10 sections of electrolytic cells. Each of these cell sections includes 26 separate cells, and each cell in turn contains 33 cathodes and corresponding anodes, and so it can be seen that each bay of this typical installation includes a total of 17,160 electrodes. It is apparent that the inspection of each electrode with the prior art techniques of voltmeter and gauss meter, requiring an inspector to walk along sections of electrolytic cells containing heated electrolyte to make individual voltage and current field measurements of each electrode associated with each cell, is both hazardous and time-consuming.

Furthermore, short-circuit detection techniques of the prior art require a high level of operator expertise. to evaluate the meter readings of a voltmeter'and/or a gauss meter to determine whether the particular meter readings actually indicate a short-circuit condition. Added to all of the foregoing difficulties associated with prior-art techniques is the additional problem that such inspection techniques are generally capable of detecting only a short circuit which has been in existence for at least 6 to 12 hours, at the earliest, depending upon the current density, thus requiring the cathode to be reworked as described above with attendant loss of electrical energy and work in process. Although substantial effort has been spent in attempts to develop a system which will detect the presence of'an electrolytic cell short circuit condition at an earlier time in the operation of the cell, the conventional gauss meter has continued to be considered the instrument which operates with the degree of reliability and repeatability demanded of production metal refining operation.

The term incipient short circuit, as the term is used herein, means a short circuit condition which exists in an electrolytic cell but which has not yet developed to a magnitude where the short circuit condition can be detected with conventional gauss meter measurement.

Itis another object of the present invention to provide a method and apparatus for detecting the presence of an electroplating cell condition which indicates the existence of a short-circuit condition in the cell.

It is still another object of the present invention to provide a method and apparatus for detecting the existence of incipient short-circuit conditions in electroplating cells.

It is a further object of the present invention to provide method and apparatus for detecting the existence of incipient short-circuit conditions in one or more of a plurality of grouped-together electroplating cells without requiring manual inspection of each and every cell.

Other objects and attendant advantages of the present invention will become more readily apparent from the following description of a working embodiment thereof, including the annexed drawing wherein:

FIG. 1 is a schematic isometric view of a cell scanning operation according to an embodiment of the present invention;

- FIG. 2 is a plan view ofa metal refining tankhouse installation equipped for cell scanning according-to the disclosed embodiment of the present invention;

FIG. 3 is a schematic view of the readout portion of the disclosed embodiment; and

FIG. 4 is a photographic reproduction of an actual facsimile recorder printout produced by the disclosed embodiment of the present invention and showing various anomolous cell conditions, as described in detail below.

Stated in general terms, incipient short-circuit conditions are detected according to the present invention by scanning an electroplating cell, or a plurality of such cells, with a heat-responsive sensor such as an infrared detector at a rate of scan and scan traverse selected to i provide information of thermal abnormalities resulting from the abnormal current density which is caused by incipient short circuits. In a preferred embodiment of the present invention, an infrared scanner is repetitively swept across the cell area undergoing investigation while simultaneously being traversed along a direction transverse to the direction of scan, with the scan and traverse rates being adjusted to provide substantially contiguous scan paths along the surfaces of the 13. Each of the cathodes 12 is connected to a negative electrical bus 14, while each of the anodes 13 is correspondingly connected to a positive electrical bus 15. The tank 11 is substantially filled with an appropriate electrolyte 16 which, in the case of a copper refining cell as aforementioned, may appropriately be copper sulphate. Those skilled in the art will realize that the cathode and anode electrodes actually used in an electrolytic copper refining operation have particular shapes and configurations, with such shape configuration details purposely omitted from FIG. I for the purpose of clarity in illustrating the present invention. Furthermore, although the disclosed embodiment of the present invention is in the context of a copper refining operation, it will be apparent to those skilled in the art that the present invention can be used in other metal refining operations, as well as in electroplating operations generally, to detect the presence of incipient short-circuit conditions therein. The reference to a cooper refining operation is by way of example only, and is without intent to limit the present invention to use in the context of copper refining.

An infrared scanner 20 is suspended from or otherwise mounted on a carrier 2l'mounted for transverse movement along a support member 22 which is, in turn, mounted for selective controlled movement along the path 23 corresponding to the lateral direction of the cell tank 11. For a typical embodiment of the present invention as installed in a production metal refining facility, the support member 22 may advantageously be provided by a travelling bridge crane which is usually present in such a facility and which travels along rails (not shown in FIG. 2) suspended above the sides of the bay or other work area in which a plurality of the cells 10 are positioned. Travelling bridge cranes typically have a hoist carrier which is capable of transverse motion in a direction 24 parallel to the supportmember 22, and this transverse motion 24 is useful for a purpose described below. It will be understood, of course, that the use of an existing crane to support the infrared scanner 20 is optional, inasmuch as the infrared scanner can alternatively be provided with a separate and independent support apparatus. It will be understood by persons skilled in the art that the lateral directional movement of the infrared scanner relative to the 'cell tank, in the described embodiment of the invention, is determined by the existing positions of the cells and the bridge crane. The scanner may be moved in any suitable direction which enables the desired surface area of the cells to be scanned, including scanner movement at a right angle to the movement depicted in FIG. 1.

The infrared scanner 20 used in the disclosed embodiment of the present invention is of the type which repetitively sweeps an instantaneous field of view 25 along a path 28 defined by the predetermined scanning are 26. Infrared scanners of this type are known to those skilled in the art, and typically include a rotating mirror which reflects the radiation collected from the field of view 25 through an optical system for focusing onto an infrared detecting element, whereat the instantaneous level of detected infrared energy is converted to an analog electrical signal. Infrared scanning apparatus of this type is available, for example, from the Barnes Engineering Company of Stamford, Conn.

The scanning are 26 is preferably at least of sufficient magnitude, considered with the elevation 27 of the infrared scanner 20 above the surface of the cell 10 being scanned, which allows the entire length of at least one cell to be scanned. By way of example, a scanning arc 26 of 90 is sufficient to scan a tank 11 having a length of 50 ft., with the scanner 20 positioned at an elevation 27 of 25 ft. above the tank. A typical state-of-the-art infrared scanner 20 thus positioned will produce an instantaneous field of view 25 of approximately 0.25 inch resolution at the tank surface directly below the scanner.

It is necessary to the detection of incipient shortcircuit conditions, as encountered in the electrolytic refining of copper, that the present invention has the ability to detect thermal abnormalities on a minimum length of cell metallic member such as an anode, a cathode, or the supports therefor, which minimum length usually has a dimension of at least one inch. An incipient short-circuit is caused by the occurrence of some abnormal conditionwhich causes a localized current density which is somewhat greater than the nominal current density in locations surrounding the thermal abnormality.'For example, the'electrolytic refining process may cause a nodule of refined copper to commencegrowing outwardly from a cathode to an adjacent' anode. When the nodule initially grows into contact with the anode, the current density at the location of nodule contact is increased and, as the growth of the nodule continues, the abnormally-high current density continues to increase. The aforementioned increased current density at the nodule location, for example, causes a relative temperature increase or hot spot, and detection of this hot spot at the earliest practical time permits Iprompt corrective measures to be taken to minimize'loss of production and wasted electricity.

To achieve the proper detection of a hot spot having the aforementioned dimension of at least one inch as measured in the direction 23 of scanner travel, it has been determined to be necessary to sweep that hot spot with at least two consecutive scans of the scanner field of view 25. Assuming a nominal field of view 25 of 0.25 inches and a scan repetition rate of 60 scans per second, in the disclosed embodiment, it becomes necessary to provide a scanner travel velocity of 75 feet per minute in the direction 23, to accomplish scanning of the entire tank surface with side-by-side contiguous scan paths 28, so that neither any unscanned area nor any scan overlap exists between any two contiguous scan paths 28. It has been found that satisfactory operation of the present invention is obtained with scan repetition rates in the range of 40-120 scans per second, with the scanner travel velocity correspondingly adjusted to the rate which is required to make each successive scan path 28 contiguous with the immediately preceding scan path.

Considering next FIG. 2, there is shown a plan view of a typical bay of atankhouse for the electrolytic-refining of a metal such as copper. The bay, shown generally at 33, contains a number of electrolytic cell sections 42, with each such tank section containing a plurality of cells which may be substantially similar to the cells 10 of FIG. 1. The cell sections 42 are arranged in four rows, as shown in FIG. 2. The support member 22 is the cross beam of a travelling crane mounted for powered movement along the two-rails 34 and 35, and the scanner carrier 21 is mounted for transverse movement along the travelling crane. The signal output from the infrared scanner, along with control signals and operatingpower required of the scanner, are supplied by a suitable cable arrangement 36 supported in a festoon system or any other arrangement which is appropriate to permitting the necessary travel of the crane. A telemetry or similar system may be used in place of cable arrangement 36. Positioned at opposite ends of the crane rail 35 is a pair of switches 37 and 38 which are actuated by movement of the crane at the switch positions and which provide signals denoting the beginning and the end of a scanning pass over a particular row of tank sections. A plurality of pulse switches 39a-39f are also positioned adjacent the crane rail to be actuated by passage of the crane therealong, with each such 'cable 40, while the outputs of the pulse switches 39a-39e are supplied to a control cable 41; these two control cables, along with the cable 36 connected to the infrared scanner, are supplied tothe display apparatu s as shown on FIG. 3..

Considering next FIG. 3, it can be seen that the lines 36 and are connected to provide inputs to a facsimile recorder 44 of the type which provides a permanent recording 45 of an input signal. The input signal to the facsimile recorder 44 is the electrical signal provided by the infrareddetecting element in the scanner 20, and this input signal is identified on FIG. 3 as the video signal supplied on the cable 36. The facsimile recorder 44, as is known to those skilled in the art, includes a mechanical drive mechanism which moves recording paper at, a constant predetermined rate past a recording device which traverses the width of the recording paper in synchronism with the repetitive scanning of the field of view 25 provided by theinfrared scanner 20. Since the video signal supplied to the recorder 44 is function of the temperature of each scanned location on the surface of a tank 1 1, the resulting recording 45 may be likened to a thermal map of the tank surface. 1

The video signal and position sync signal may also be supplied along lines 36, 46a and 4ll, 46b, respectively, to a cathode ray tube (CRT) display 47, if desired, which can be operated to provide an instantaneous visual display of the thermal signal provided by each scan path 28 across a cell 10. i

Considering the operation of the embodiment as herein described, it is assumed that the crane 22 and the carrier 21 are initially positioned as shown in FIG. 2. After the infrared scanner 20 (not shown in FIG. 2) and the facsimile recorder 44 are turned on, the crane 22 is controlled in the conventional manner to commence movement along the rails 34 and 35 toward the opposite end of the bay 33. Movement of the crane past the switch 37 supplies a scan start signal along the line 40 which may advantageously be connected to commence paper movement in the facsimile recorder, thus automatically initiating recording of a scan run. Fur.- ther motion of the crane actuates the first pulse switch 39a, positioned in known relation to the first tank section 42 to be traversed by the scanner, and the signal provided by this and the subsequent pulse switches functions as a synchronization signal to insure that the CRT display 47 allows a complete recording sweep of the CRT screen for each section 42 of individual electrolytic cells.

The foregoing scanning operation, identified on FIG. 2 as scan No. 1.continues until the crane 22 actuates the switch 38 to signal the end of the first row of cell sectionsThe paper-drive of the facsimile recorder 44 is automatically terminated, and the scanner carrier 21 must next be repositioned along the crane 22 to be in alignment with the second row 48 ofcell sections. Once this has been accomplished, crane travel is again initiated and actuation of the switch 38 signals commencement of the next scanning run and the start of the recording paper for the next scanning run, identified on FIG. 2 as scan No. 2." Following the commencement riod of 1 hour. This cell section consists of 13 numerically-designated cells, with each cell having 33 numerically-designated cathode positions. In the thermogram of FIG. 4, the light areas represent the presence of heat relative to the darker (cooler) portions depicted on the thermogram. The thermogram was made with the facsimile recorder 44 adjusted to provide a contrast such that the surface area of the electrolyte in the cells appears white, as exemplified at 55 on FIG. 4. This preset contrast, made with reference to the known or readily ascertainable temperature of the electrolyte in the cells, provides a convenient reference temperature against which other temperatures on the thermogram may be compared. The horizontal dark lines on the thermogram, such as the line 56, represent hanger bars which are positioned above the electrolyte to support the cathodic starter sheets. The hanger bars, as represented by the dark line 56, normally are considerably cooler than the electrolyte in the cells.

The existence of thermal conditions corresponding to incipient short-circuits is illustrated by the following. Considering cells 12 and 13 at positions 19 and 20, respectively, white areas 57 and 58 are present where dark hanger bar lines should normally occur. An inspection of the corresponding cell positions indicated that the starter sheets connected to the hanger bars at the foregoing positions were bent, resulting in abnormal current density conditions which produced the heating of the hanger bars.

Another obvious abnormality can be seen in cells eight and nine at position 22, indicated at 59 on FIG. 4. Inspection of this location confirmed that the hanger bars of the adjacent cells were in direct contact with each other.

In cells five and six, at position 21, the white areas 60 and 61 indicate hot spots in the hanger bar. Inspection of this location revealed that the hanger bar was contacting a support lug of the cell anode, in each of cells five and six.

In cell four, position six, about one-third of the hanger bar appears in a relatively gray tone as at 62. Examination of the cell position revealed a startersheet which apparently had been damaged in initial loading into the cell. Position seven of cell four, as at 63, is also lighter in gray tones than the normal bar. Again, anode contact with the hanger bar was found to be the cause.

Further in cell number four, at position 24, the faintly visible hanger bar depicted at 64 was caused by a cathode sheet having a bent corner, giving rise to a current density abnormality which produced the detected hot spot.

The foregoing recitation and identification of specific hot spots on FIG. 4, and the operational cause of each hot spot, is only exemplary of the cell abnormalities which are detectable according to the present invention. Moreover, it can be seen that there are numerous other hot spots depicted on FIG. 4 which, although not specifically discussed herein, are indicative of other cell positions which require personal inspection and corrective action. Scanning an entire bay 33, consisting of four separate rows of cell sections, takes approximately 16 minutes at feet/minute, plus time to reposition the scanner, according to the disclosed embodiment of the present invention, and the resulting thermograms can be relatively rapidly examined to determine the specific locations of thermal abnormalities indicative of possible incipient short circuits. It will be understood, of course, that short circuit conditions which have developed to a magnitude to be detectable with conventional gauss meter-measurement typically cause thermogram hot spots of even greater prominence than the hot spots caused by incipient vshortcircuit conditions, and so such short circuits are also detectable by the present invention. The inspection personnel, after reviewing the thermograms, can proceed immediately to the suspect cells and electrode positions without wasting valuable time in a routine, manual inspection of each and every cell position as previously done according to prior art techniques.

Use of a thermal detection method and apparatus according to the above-disclosed specific embodiment of the present invention has demonstrated that incipient short-circuit conditions can be detected as much as 24 hours prior to earliest possible'detection of such' condi- I tions with conventional gauss meter or voltmeter apparatus; Moreover, a complete thermal inspection of all cells can be made one or more times during each work shift, without requiring a substantial expenditure of manual inspection labor and without necessitating hazardous walking on the cells. The thermograms produced according to the present invention provide a permanent record of each cell position at various times' during the operating life of the cell, and constitute a source of data against which the work of the inspection crews and the refined copper production of the cells can be evaluated. In the foregoing actual working embodiment, the nominal cell current density of 14 amperes per square foot was approximately one-half of the maximum current density for which the tankhouse was designed, such reduced current density being maintained for experimental purposes, and so it is reasonable to assume that the 24 hour advantage provided by the present method over conventional gauss meter techniques would correspond to a 12 hour advantage when the tankhouse is operated at full current density.

Moreover, it will be understood that the foregoing relates only to a preferred embodiment of the present invention, and that numerous alterations and modifications may be made therein without departing from the spirit and the scope of the present invention as set forth in the following claims.

We claim:

1. Method of detecting the presence of an incipient short-circuit condition of an electrode immersed in electrolytic solution, comprising the step of repetitively scanning the electrode to examine the amount of infrared energy radiating from the electrode, said scanning occurring at a rate of no less than two nonoverlapping scans of at least about 0.25 inch of width per inch of electrode in 1/120 of a second.

2. In an electrolytic refining operation including at least one electrolytic tank containing an electrolyte and having a plurality of spaced apart electrodes disposed in the electrolyte, the method for detecting the location of an incipient short-circuit condition resulting in an abnormal localized current flow and manifested by an "abnormal output of infrared radiation from such locaportion of the surface of said electrolytic tank; and

selecting the width of said scan path relative to a desired minimum width of detectable incipient shortcircuit location so that a said location is scanned by at least two successive repetitive scan paths.

3. The method as in claim 2, wherein substantially no overlap of said two successive scans occurs.

4. The method of claim 2, wherein there is substan tially no unscanned area between said two successive scans.

5. The method as in claim 2 wherein a detectable said location of an incipient short-circuit condition has adimension of at least about 1 inch in extent, and the width of each said scan path is at least about 0.25 inch.

9., Apparatus for detecting the existence of an incipient short-circuit condition in an electrolytic tank containing a plurality of spaced apart electrodes disposed in an electrolyte within the tank, with an incipient short-circuit condition being manifested by an abnormal output of infrared radiation from a location on the electrolytic tank, comprising the combination of:

infrared responsive means supported in elevated spaced apart relation above the electrolytic tank and operative to repetitively sweep a portion of the open electrolytic tank with a scan path having a certain width;

traversing means mounted above the electrolytic tank and supporting said infrared responsive means, said traversing means being operative to move said infrared responsive means over the electrolytic tank at a substantial angle to said scan path and at a predetermined rate of speed which causes a said location of previously determined minimum detectable size to be scanned by at least two successive scan paths.

10. Apparatus as in claim 9, in which such electrolytic tank is one of plural such tanks arranged in a row in a tankhouse, and said traversing means is mounted in spaced relation above said row and is operative to 6 traverse said scan path across the surfaces of each of said plural electrolytic tanks in predetermined sequence.

10 l 1. Apparatus as in claim 9, wherein said infrared responsive means scans a path having a width of at least about 0.25 inch on the electrolytic tank.

12. Apparatus as in claim 11, wherein said traversing means is operative to traverse said scanning path at a rate which results in substantially no overlap of said 1 two consecutive scan paths.

13. Apparatus as in claim 11, wherein said traversing means is operative to traverse said scanning path at a rate which leaves substantially no unscanned area between said twoconsecutive scan paths.

14. Apparatus as in claim l1,wherein said traversing means is operative to traverse said scanning path at a rate whereat said two consecutive scan paths are substantially contiguous.

15. Apparatus as in claim 11, wherein said traversing means is operative to traverse said sensor means at a predetermined rate of speed which causes said at least two consecutive scan paths to occur over a distance of no more than 1 inch as measured in the direction of traverse.

16. Apparatus for detecting the presence of an incipient short-circuit condition in a section of electrolytic cells each of which cells contain plural electrode elements, comprising:

traversing means mounted in elevated relation to the section of electrolytic cells and selectively operative to traverse a certain predetermined path relative to such cells; switch means positioned to provide a control signal condition in response to the presence of said traversing means at a certain location corresponding to the beginning of said traverse path over a section of cells; sensor means carried by said traversing means and operativeto provide an output signal responsive to the amount of thermal energy which strikes a predetermined sensing area of said sensor means;

scanning means operatively associated with said sensor means to repetitively sweep said sensing area at a predetermined rate along a predetermined scanning path in angular relation to said path of traverse;

readout means connected to receive said output sig-.

nal and selectively operative to provide an output display which is a function of time and of said output signal;

circuit means connecting said switch means to said readout means; and

said readout means being operative to commence providing said output display in response to said control signal condition.

17. Apparatus as in claim 16, for use with a number of sections of electrolytic cells, wherein:

said traversing means is mounted to traverse each section of cells in said elevated relation and along said certain predetermined path;

said switch means is positioned to provide said control signal condition in response to said traverse means being at a certain location relative to the beginning of a first section of cells to be traversed. I

18. Apparatus as in claim 16, for use with a number of sections of electrolytic cells, comprising:

said traversing means is mounted to traverse each section of cells in said elevated relation and along said certain predetermined path;

said readout means operative to provide a cell section display condition in response to each of said additional control signal condition. 

1. Method of detecting the presence of an incipient shortcircuit condition of an electrode immersed in electrolytic solution, comprising the step of repetitively scanning the electrode to examine the amount of infrared energy radiating from the electrode, said scanning occurring at a rate of no less than two nonoverlapping scans of at least about 0.25 inch of width per inch of electrode in 1/120 of a second.
 2. In an electrolytic refining operation including at least one electrolytic tank containing an electrolyte and having a plurality of spaced apart electrodes disposed in the electrolyte, the method for detecting the location of an incipient short-circuit condition resulting in an abnormal localized current flow and manifested by an abnormal output of infrared radiation from such location, comprising the steps of: repetitively scanning a surface of the electrolytic tank along a path of certain width to measure the amount of infrared radiation emanating therefrom, the width of said scanning path being only a fractional portion of a dimension of said electrolytic tank; traversing said scan path in a direction at a substantial angle to said scan path so that each successive repetitive scan passes along a previously unscanned portion of the surface of said electrolytic tank; and selecting the width of said scan path relative to a desired minimum width of detectable incipient short-circuit location so that a said location is scanned by at least two successive repetitive scan paths.
 3. The method as in claim 2, wherein substantially no overlap of said two successive scans occurs.
 4. The method of claim 2, wherein there is substantially no unscanned area between said two successive scans.
 5. The method as in claim 2 wherein a detectable said location of an incipient short-circuit condition has a dimension of at least about 1 inch in extent, and the width of each said scan path is at least about 0.25 inch.
 6. The method as in claim 5, wherein said scan path is traversed in a direction substantially perpendicular to said scan path.
 7. The method as in claim 5, wherein said repetitive scan occurs at a rate in the range of about 40-120 scans per second inclusive, and said predetermined rate of traverse is the rate at which each consecutive scan is contiguous with immediately preceding scan at the particular rate of repetitive scan.
 8. The method of claim 5, wherein said two consecutive scans are substantially contiguous with each other.
 9. Apparatus for detecting the existence of an incipient short-circuit condition in an electrolytic tank containing a plurality of spaced apart electrodes disposed in an electrolyte within the tank, with an incipient short-circuit condition being manifested by an abnormal output of infrared radiation from a location on the electrolytic tank, comprising the combination of: infrared responsive means supported in elevated spaced apart Relation above the electrolytic tank and operative to repetitively sweep a portion of the open electrolytic tank with a scan path having a certain width; traversing means mounted above the electrolytic tank and supporting said infrared responsive means, said traversing means being operative to move said infrared responsive means over the electrolytic tank at a substantial angle to said scan path and at a predetermined rate of speed which causes a said location of previously determined minimum detectable size to be scanned by at least two successive scan paths.
 10. Apparatus as in claim 9, in which such electrolytic tank is one of plural such tanks arranged in a row in a tankhouse, and said traversing means is mounted in spaced relation above said row and is operative to traverse said scan path across the surfaces of each of said plural electrolytic tanks in predetermined sequence.
 11. Apparatus as in claim 9, wherein said infrared responsive means scans a path having a width of at least about 0.25 inch on the electrolytic tank.
 12. Apparatus as in claim 11, wherein said traversing means is operative to traverse said scanning path at a rate which results in substantially no overlap of said two consecutive scan paths.
 13. Apparatus as in claim 11, wherein said traversing means is operative to traverse said scanning path at a rate which leaves substantially no unscanned area between said two consecutive scan paths.
 14. Apparatus as in claim 11, wherein said traversing means is operative to traverse said scanning path at a rate whereat said two consecutive scan paths are substantially contiguous.
 15. Apparatus as in claim 11, wherein said traversing means is operative to traverse said sensor means at a predetermined rate of speed which causes said at least two consecutive scan paths to occur over a distance of no more than 1 inch as measured in the direction of traverse.
 16. Apparatus for detecting the presence of an incipient short-circuit condition in a section of electrolytic cells each of which cells contain plural electrode elements, comprising: traversing means mounted in elevated relation to the section of electrolytic cells and selectively operative to traverse a certain predetermined path relative to such cells; switch means positioned to provide a control signal condition in response to the presence of said traversing means at a certain location corresponding to the beginning of said traverse path over a section of cells; sensor means carried by said traversing means and operative to provide an output signal responsive to the amount of thermal energy which strikes a predetermined sensing area of said sensor means; scanning means operatively associated with said sensor means to repetitively sweep said sensing area at a predetermined rate along a predetermined scanning path in angular relation to said path of traverse; readout means connected to receive said output signal and selectively operative to provide an output display which is a function of time and of said output signal; circuit means connecting said switch means to said readout means; and said readout means being operative to commence providing said output display in response to said control signal condition.
 17. Apparatus as in claim 16, for use with a number of sections of electrolytic cells, wherein: said traversing means is mounted to traverse each section of cells in said elevated relation and along said certain predetermined path; said switch means is positioned to provide said control signal condition in response to said traverse means being at a certain location relative to the beginning of a first section of cells to be traversed.
 18. Apparatus as in claim 16, for use with a number of sections of electrolytic cells, comprising: said traversing means is mounted to traverse each section of cells in said elevated relation and along said certain predetermined path; additional control switch means positIoned to provide additional control signal conditions in response to said traverse means being at a certain location relative to each of the sections of cells; and said readout means operative to provide a cell section display condition in response to each of said additional control signal condition. 